"At least four people have been killed in an early-morning raid by security forces on Pearl Square, the focal point of anti-government demonstrations in Bahrain, sparking street battles with riot police.

Armoured trucks have been seen in central Manama and key roads are blocked by security forces. The crackdown follows a dramatic and violent turn in three days of protests calling for widespread reform within Bahrain's ruling minority. Dozens of wounded protesters were being taken to hospitals across the city on Thursday morning.

Riot police stormed the rallying point for the demonstrations, a landmark known as Pearl roundabout, at around 3.15am, firing teargas and birdshot, and wielding clubs and knives, which they used to cut through tents set up by demonstrators.

"We were asleep and they started slicing through our tent," said Nabeel Ebrahim, who was sleeping alongside two trauma surgeons from Salmaniya hospital. "They started firing gas from the overpass and attacking us from all directions."

One of the doctors, Sadiq al-Ikri, is receiving treatment in the critical care unit of the hospital he works in. "He was handcuffed and then kicked repeatedly in the head, face and body," one of his colleagues said. "We have nine other seriously wounded patients."....."